The first time the unknown bacteria was isolated, one of the colonies was observed to be bright yellow. This was important because it gave a clue as to which one was gram positive because looking for a yellow color was part of the gram positive dichotomous key. However, this conclusion that the yellow colony was positive and the white colony was negative was not certain until the conduction of the second gram stain. Also, even though Micrococcus was the only possible bacteria with colonies that have a distinctive pigment, all of the tests had to be performed to make sure that the other characteristics of this bacteria were consistent with the reported results that Micrococcus should have, according to the table. During the catalase test, the immediate bubbling of the bacteria was observed, meaning that it was catalase positive. The second test was to see if the microbes were rod shaped or not. …show more content…
subtilis. The next test on the key was whether or not the colonies were bright yellow. Since the colonies on the plate were in fact yellow, the conclusion that the bacteria must be Micrococcus luteus was made. According to Bergey’s Manual, this yellow pigment is a characteristic that is unique to Micrococcus in comparison to the other gram positive bacteria on the list. For the fourth and final test needed to further confirm that the gram negative bacteria was Micrococcus, the results from the MSA plate were examined. The agar did not change color from pink to yellow, meaning that no mannitol fermentation occurred. After comparing the result of no mannitol fermentation to Bergey’s Manual, as well as the other test results, it was possible to conclude that the gram positive bacteria was Micrococcus